Not Applicable
The present invention pertains to a support for microelectronic workpieces, such as semiconductor wafers, compact recording discs, or other such workpieces. More particularly, the present invention relates to a support for microelectronic workpieces, and corresponding apparatus using the support, wherein the support assists in safely restricting movement of the workpieces thereby preventing or otherwise inhibiting tipping, shaking, or wobbling of the workpieces.
Microelectronic workpieces, such as semiconductor wafers and the like, undergo a substantial number of processes before ultimately forming a microelectronic component or circuit. During such processing, one or more of the workpieces must be supported, for example, as they are transferred to or from a processing station of a tool, as they are processed at the station, wall they are stored at various staging areas within the each tool as well as along the production line, as they are transferred between the various processing tools of the production line, etc.
One tool that is used for processing microelectronic workpieces is exemplified in U.S. Pat. No. 5,660,517 to Thompson et al. In the particular tool illustrated in the ""517 patent, the workpieces are removed from wafer carriers (cassettes) by elevator heads, whereupon the workpieces are transferred from the elevator heads by transfer mechanisms, for processing at various processing stations within the tool. The disclosure of U.S. Pat. No. 5,660,517 is incorporated herein by reference.
The transfer mechanism illustrated in the ""517 patent includes components that are now common to a number of widely used systems. More particularly, each transfer mechanism employs a microelectronic support that comprises two transfer arms, each transfer arm comprising a grooved strip for engaging the workpieces as the workpieces are lifted from the elevator heads and transferred to, for example, one or more of the workpiece processing stations of the tool. The grooved strips are initially deployed beneath and on opposite sides of the centers of the workpieces. Each strip has a series of grooves, each groove positioned to receive a respective workpiece. Usually, there are between thirteen and fifty-two grooves that are used to reflect current industry standards for wafer carriers.
In such known microelectronic supports, each groove is comprised solely of a pair of parallel walls, which provide clearances for the workpieces. As a result of the clearances, the workpieces can tip, shake, or wobble in the grooves, particularly during wafer transfer operations. Usually, such tipping, shaking, or wobbling is not problematic. However, under some conditions, tipping, shaking, or wobbling can result in damage to some of the workpieces and/or the generation of unwanted particles, which can be a source of contamination. The present invention has resulted from efforts to prevent or otherwise inhibit the workpieces from tipping, shaking, or wobbling in the grooves of such grooved members.
A workpiece support and an apparatus including such a workpiece support are set forth. The workpiece support includes a set of grooved members for supporting a series of workpieces. The workpieces may be similarly shaped, e.g. circular or rectangular, and similarly sized, each having a front face and a back face. An outer perimeter of each workpiece may be beveled at both faces, beveled at one face, unbeveled, convex, or concave.
Although the grooved members are particularly useful for supporting semiconductor wafers, compact recording discs, or other microelectronic workpieces, the grooved members prove to be additionally useful for supporting diverse workpieces. Although the grooved members are useful on the transfer arms of a transfer mechanism, as mentioned above, the grooved members prove to be additionally useful on an elevator head, as mentioned above, or in other diverse applications, such as those described below.
Each grooved member has a series of similar grooves. Being adapted to receive such a workpiece, each groove has a bearing wall and a wedging wall shaped and oriented so that a line normal to the wedging wall intersects but is not normal to the bearing wall. For many applications, two grooved members are employed, which are parallel to one another, spaced from one another, and oriented so that the grooves of the grooved members are generally aligned. To this end, a first grooved member is oriented so that the front faces of the received workpieces bear against the bearing walls of the grooves of the first grooved member and so that the received workpieces touch the wedging walls of the grooves of the first grooved member. A second grooved member is oriented so that the back faces of the received workpieces bear against the bearing walls of the grooves of the second grooved member and so that the received workpieces touch the wedging walls of the grooves of the second grooved member. Thus, the workpieces received by the grooves of the grooved members are wedged so as not to tip, shake, or wobble.